I would not bother to much about the driving licence if you have a licence which alows you to drive your 3 Wheeler in you own country, it will be mandatory in all other countrys.
You have a permit so your legal! The only big matter is, if you will need a Helmet, Safty Jacket, First aid kit or other required acessories prescripted by the law in which country you will drive in or through...at least for the EU...is there a difference for the US?
Dodgy 'advice'. The correct way a UK licence should be seen in other EU countries is if the issue date precedes 19 Jan 2013, a car (full group B) or a motorcycle licence (full group A) will do. If the issue date is after 19 January 2013, only a motorcycle licence will do, either full, or with note 79, 'for tricycles only' on it. A car test passed after 19 Jan 2013 if the holder is over 21 only allows the driving of a tricycle inside UK,
it is not valid anywhere other than the UK.I think it is more than possible, a policeman in other EU countries than the UK will see things your way for a simpler life, the rules are both complicated and idiotic. Doesn't mean it's right though.
I believe an American motorbike licence is a lot easier to get at a younger age than in the EU. This is an explanation of the hoops that need jumped through in the UK and other EU countries.
Getting a motorbike licence Added, unless very well advised by a practising lawyer in the intended country of visitation, I think as far as helmet wearing is concerned, one has to utterly follow the laws of that country.